Erika Lorraine Milam on Creatures of Cain: The Hunt for Human Nature in Cold War America

After World War II, the question of how to define a universal human nature took on new urgency. Creatures of Cain charts the rise and precipitous fall in Cold War America of a theory that attributed man’s evolutionary success to his unique capacity for murder. Drawing on a wealth of archival materials and in-depth interviews, Erika Lorraine Milam reveals how the scientists who advanced this “killer ape” theory capitalized on an expanding postwar market in intellectual paperbacks and widespread faith in the power of science to solve humanity’s problems, even to answer the most fundamental questions of human identity.

What surprised you when you were researching the book?

I never intended to write about violence. The book started as a kernel of a story about the development and reception of an educational program called Man: A Course of Study, or MACOS. When Americans learned that the Soviet Union had launched the world’s first man-made satellite into orbit, they feared the technological prowess of Soviet engineers and scientists would quickly outstrip their own, unless they poured significant energy into science education. The result was a series of educational programs developed by experts and made available for use in elementary school classrooms around the country: the PSSC, BSCS, and others. MACOS was the first to tackle questions central to the social sciences. Led by cognitive psychologist Jerome Bruner, it focused students’ attention on three questions: “What is human about human beings? How did they get that way? How can we become more so?” I wanted to know more. The program, I discovered, used a wide array of materials—among them: films, booklets, and board games—to get students to contemplate these larger questions about the diverse communities in which they lived. But quickly I realized, too, that when MACOS was adopted by local school systems it was met with protests from community members who objected to the violent content of the materials. It was difficult for me to square the project’s intentions with the accusations hurled at it only a few years later. My research snowballed. Debates over violence during the Cold War—its causes and consequences—served as proxies for scientists thinking about questions of sex, race, and their own contested authority to answer these fundamental issues. This book is the result.

You interviewed a lot of people for the book, what was that like?

Thanks for asking me this! Creatures of Cain would have been a very different book without the generosity of the scientists and writers who took the time to speak with me about their research. In reconstructing past events, historians necessarily rely on archival research. This works brilliantly when people have already deposited their correspondence and papers in an archive, but those collections are more rare than you would think, are often highly curated, and are usually available only after someone has died. (Not everyone is keen to have future historians read through old letters.) When working on recent history, talking with scientists while they are still alive allows historians like myself access to voices and perspectives that would otherwise be difficult to include. Much about a scientist’s life is never recorded in a paper trail: from the books and experiences people found inspiring when they were teenagers to the friends and colleagues who sustained them during and after graduate school. Talking with people about their histories is thus invaluable, especially in trying to recreate informal networks of collaboration that I would have otherwise missed. Plus, I find it thrilling to meet people in person. The lilting cadence of a voice, the disorderliness of an office, or the art on a wall: each of these things leaves a singular impression impossible to glean from the written word alone.

How did you choose the images for the book?

For centuries images have played a crucial role in communicating scientific ideas, including concepts of human nature. After the Second World War, with the exciting coverage of paleoanthropological fossil discoveries in Africa and nature documentaries about modern human cultures from all over the world, still and moving images stirred audiences’ interests in anthropological topics. When selecting images for the book, I chose to emphasize drawings and illustrations that depicted the theories under discussion or scientists hard at work. Their striking visual styles reflect both the artistic conventions of the time and the highly visual nature of scientific conversations. More so than photographs, which can easily be read as flat representations of the past, I hope these images center readers’ attentions on the creativity required to bring theories of human nature to life.

How did you become a historian of science?

I came to the history of science fortuitously. In my undergraduate and early graduate work, I studied biology. Only in my second year of graduate school in the Ecology and Evolutionary Biology program at the University of Michigan did I come to realize that there was a whole community of people, like me, who were interested in the humanistic study of science, technology, and medicine. I started reading books on the history of evolutionary theory, on gender history, and on the history of American science. I was gripped. Now I study how intellectual and social concerns are tightly bound together within scientific inquiries. I find especially fascinating research on the biological basis of sex and aggression in human behavior—each of which touches on the broader question of what it means to be human in a naturalistic world.

What are the lessons for us today that we learn from Creatures of Cain?

When I talk about my project, people ask me whether the growing violence of the struggle for Civil Rights domestically or the escalating Vietnam War made it easier for scientists and citizens to embrace the idea that humans were naturally murderous. The “killer ape” theory, as it came to be known, posited that the crucial divide between humans and all other animals lay in our capacity to kill other members of our own species. Did the violence of the era, perhaps, explain why it was easy to imagine the history of humanity as characterized by violence and only punctuated by moments of peace? I answer by saying that only a decade earlier, in the wake of the death and horrific atrocities of the Second World War, scientists chose instead to emphasize the importance of emphasizing the fundamental unity of humankind. Only through a common struggle against the environment, they argued, had our human ancestors survived life on the arid savannah—we humans may have clawed our way to the present, but we did it together. Biological theories of human nature have been used both to dehumanize and to promote progressive anti-racist conceptions of humanity as a whole. As these accounts demonstrate in juxtaposition, there is no consistent correlation between the desire to biologize human nature and either periods of violence or schools of ideological persuasion.

Equally important, fundamental questions about the nature of humanity—in the colloquial scientific books I make the center of my analysis—have helped recruit and inspire generations of students to pursue careers in the natural and social sciences. Even though such discussions rarely appear in the pages of professional scientific journals, they are central to how scientific and popular ideas about human nature change. Drawing a sharp distinction between specialist and non-specialist publications would thus distort the history of ideas about human nature in these decades. After all, scientists read (and reviewed) colloquial scientific publications, too, especially when exploring new ideas outside their immediate expertise.

When observations that chimpanzees also killed chimpanzees became broadly known in the latter half of the 1970s, it spelled the end of the killer ape theory. Although the idea that aggression provided the secret ingredient to the unique natural history of humanity has faded, this theory helped lay the groundwork for how scientists conceptualize human nature today.

Bonus question (if you dare): Please summarize the book in a tweet.

Oh wow! Okay, here’s a sentence from the introduction that actually fits: “In its broadest scope, Creatures of Cain demonstrates that understanding the historical fate of any scientific vision of human nature requires attending to the political and social concerns that endowed that vision with persuasive power.”

Erika Lorraine Milam is professor of history at Princeton University. She is also the author of Looking for a Few Good Males: Female Choice in Evolutionary Biology.